This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
A multitude of commercial applications are available for heavy-duty conveyor belts which transport products and materials, including minerals, coal, and a wide variety of manufactured products from one point to another. Such conveyor belts can include buckets or corrugated walls to facilitate transportation of certain materials. In many cases the conveyor belts are relatively long, extending over a distance of several miles, and they can represent a high cost component of an industrial material handling operation. The conveyor belts and their respective drives are susceptible to normal wear and tear as well as damage from the material being transported, and/or harsh environmental conditions. In the event the conveyor belt suffers catastrophic damage or otherwise becomes inoperable, the costs of repairing the conveyor belt, cleaning up any spilled material, and related downtime are substantial. For instance, sharp edges of the material being transported can gouge the surface of the belt and that can result in a rip developing.
When a rip or damaging event is detected, the belt can often be repaired. Where the belt damage is not detected and repaired promptly, the rip typically propagates along the length of the belt with continued use of the conveyor system and this renders the repair even more difficult and costly. It is accordingly desirable to detect damage to the belt as soon as possible after it occurs and to quickly repair the damaged area of the belt. By doing so the extent of the damage to the belt can be minimized and the spillage of material being conveyed can be reduced.
Over the years, a number of systems have been developed for detecting belt damage and for automatically stopping further movement of the belt after the damage occurs. It is well known to employ sensors within conveyor belts as part of a rip detection system. In a typical system, sensors in the form of loops of conductive wire are affixed or embedded in the belt and provide a rip detection utility as part of an overall rip detection system. Rip detection is achieved through the inferential detection of an “open circuit” condition in one or more of the sensor loops in the belt. Typically, an electrical energy source external to the belt is inductively or capacitively coupled to a sensor loop in the belt. A break in the conductive wire loop of the sensor may be detected by a remote transmitter/receiver (exciter/detector). Disposition of a plurality of such sensors at intervals along the conveyor may be effected with each sensor passing within read range of one or more exciter/detectors at various locations. A rip or tear will encounter and damage a proximal sensor loop and the existence of the tear will be detected when the proximal sensor loop damage is detected as an open circuit by the reader at its next pass. In this manner, the existence of a tear will be promptly detected and repaired with further damage to the belt being minimized.
U.S. Pat. No. 8,256,607 discloses a sensor system for a conveyor belt in which a monitoring system is provided for a moving conveyor belt having a plurality of embedded reinforcing cords and identification tags. A tag reader detects and identifies the identification tags passing by the tag reader while a belt monitor scans the cords to detect a plurality of magnetic reference points and a damage event of at least one cord. A control unit in communication with the belt monitor and the tag reader analyzes the belt monitor to identify the plurality of magnetic reference points and the damage event. The control unit also acquires a belt location on the moving conveyor belt from a belt map based on the detected and identified identification tag and a magnetic reference point from the plurality of magnetic reference points. When a damage event is identified, a location of the damage event is determined by the control unit based on the acquired belt location.
U.S. Pat. No. 8,069,975 discloses a conveyor belt rip detection system which provides a conveyor belt rip detection system with belts having rip detection inserts that can be more easily integrated into conveyor belts at low cost. These rip detection inserts do not adversely affect the durability of the conveyor belt and can be easily replaced in the event of belt damage. This rip detection system also provides a highly reliable early image of belt damage that can facilitate quick repair before extensive belt damage occurs. The present disclosure more specifically discloses a conveyor belt comprising (1) an elastomeric body having a load carrying surface and a parallel pulley engaging surface; (2) a reinforcement ply disposed within the elastomeric body; and (3) a multitude of rip detection inserts, wherein the rip detection inserts are spaced along the longitudinal length of the conveyor belt, wherein the rip detection inserts contain a multitude of rip detection wires that are comprised of a magnetically permeable material, wherein the rip detection wires are aligned in the rip detection inserts at a bias angle of 15° to 75° from being perpendicular to the longitudinal direction of the belt, and wherein the rip detection wires are spaced incrementally across the width of the belt.
U.S. Pat. No. 7,810,634 discloses a sensor system for a conveyor belt in which a monitoring system is provided for a moving conveyor belt having a plurality of embedded reinforcing cords and identification tags. A tag reader detects and identifies the identification tags passing by the tag reader while a belt monitor scans the cords to detect a plurality of magnetic reference points and a damage event of at least one cord. A control unit in communication with the belt monitor and the tag reader analyzes the belt monitor to identify the plurality of magnetic reference points and the damage event. The control unit also acquires a belt location on the moving conveyor belt from a belt map based on the detected and identified identification tag and a magnetic reference point from the plurality of magnetic reference points. When a damage event is identified, a location of the damage event is determined by the control unit based on the acquired belt location.
Prior art rip detection systems do not provide sufficient detection means to alert conveyor belt operators to damage occurring at the longitudinal edges of a conveyor belt. This region of the belt is especially critical to bucket conveyor belts, conveyor belts employing corrugated walls, and fabric belts generally. Damage to belt edges of any type of conveyor belt can lead to transverse tearing, which can cause products or materials to fall or become damaged, and the repair of such tearing can be costly and time consuming. Furthermore, prior art detection systems do not sufficiently detect conveyor belt tracking failures in which a conveyor belt veers from a designated track during belt operation. When a belt is removed a given distance from its track, the belt itself and the property carried upon it can be damaged. Additionally, stringers, idlers and other supporting structures can be also damaged if the belt tracks too far out of proper alignment. There is accordingly a need for a conveyor belt edge detection system which can also be used to monitor belt tracking during conveyor belt operation.